Air controlled shifting mechanism



H. w. cARDwELl. Erm.

AIR comoLLEn SHIFTING MECHANISM May 23, 195o 2 Sheets-Sheet 1 Filed July30, 1947 grwam/IDW H. WQCARDWELL ET AL AIR C'ONTROLLED SHIFTINGMECHANISM 2 Sheets-Sheet 2 Filed July 30, 1.947

llll Il w m, f uw d .m 4H M 3 A l l! A lll||||llHHH||H n ww. Q/u c. d My 3 Patented May 23, 1950 iunirreo stares sessel :TENT o FFICE .1 Thislinventiim re'l'ates to rgear-fshifting mechanismswherein ithe-irati'oofidrive yrfromva 4source of power to a v4'drivennrenrber dnay Hoevariedl at 'the will offthe operator.

such a gear shifting mechanism that/can befop 'era-ted by a-fl`uid=underpressure, preferablyair, from` arremotercohtrol station. l

. Itis va further Yobject fof 'this `invention 'to provide 'a :gear*shifting mechanism `that -is .simple and economical --fconstruction-and providing vfor-irnaximum efciency and-dependability in operation.

'Itis a* further -robject iof this invention v.to profvide such ia zgearshifting @mechanism that may bel-readily `attached to r'a-standardselective Agear dri-ve ytofreplaee fthe iconventional .manual loyother'shiftinganechanism.

A*It .is-vastill further yobject of this .invention to :providesuch-.agear-shifting .mechanism wherein the fluid nnnder pressure willactuate Ameans to Veffect -theidesired v.gear `ratio and whereinccntinued- Yapplication vof. .the .fluid ...pressure .will not cause:undue -wearsof the `oper-ated parts.

In `the :accompanying drawings .there are iillnstrated -,preferred-..embodiments .of -this invention,

and .in which:

Figure `1 .is .a top ,plan `view .of one .embodiment of the .gearnshifting :mechanism .with .the `cover .plateiremovem Y Figure 2 is-a-ilongitudinal vertical .sectional view taken along the line 22ofEigure'l look- ,ing in the direction of .the arrows;

Figure' .is `a vertical sectional Iview similar to Figure Zhutillustrating-a modified embodiment;

desired, .the .c1ove1..p1ate3 .may be provided with a gasket as .shownat.

lhe housing .i is provided at .opposite -ends .with .opposed .pairs *oflopenings In .the pposed openings of each pair, .a .pairpf axially.aligned .guidefrods .l .are mounted, each .guide rod havingheadportion' '3 by .which it .is held in l T@lationavithlthe.housingmember E by cap screws J3 .or 'the'.like. .The .adjacent ends IU,oithealignedguiderodsareaxiallyspacedapart falsubstantial distance .as.clearly shownfinFi'g- -2 ure '2. Each 'guide rod also 'is v,providedwith an axial v.bore :III and :fa-'fitting :I2 .forra purpose to belater described.

A ltubular 4shifting member -rI 3 is telescopically arrangedrover theadjacent :ends-:of opposed rods I for Vsliding movement thereon. :Eachtubular member I3 `is providedwith an.-enlarged yportion I4 `at each end:thereof'and anenlarged bore l5 in ysaid enlarged portion. Each of said.enlarged bores I5 contains a `packing `material I6 held therein .by a'packing ring I1. .The purpose of the packing -IB is to-effect a sealbetween 4the tubular members I3 and the .-guiderodfl sufficient toretain the necessary uid pressure within'the tubular 'memben The packingI-6 Imay .be of any 4conventional orsuitab1e type. -Each tubularshiiteremember .'I3 is furtherprovidedwith a partition wall 18substantially midway ofits length and said partition wall 4is betweenthe opposed endsof vthe aligned-.guide rods .1,.thus.providing a pair-of expansible Apressure .chambers 49 .and 2t withinsaid tubularshifter-member. A-compression spring 24. .is .located in Ieach pressurechamber 'and 'each .abuts .at one .end -against .the end of one oftheguide 4rods landat its .other end.againstthe-.partition wall 18. Eachtubular shifter member .I3 `is .turther .provided with a shifterfork.22. Asishown, each shifter fork .is integral with its tubularshifter -member I3 'but it is to be .understood thatsuch construction isnot .necessary for the .practice of this invention since vthe `shifter:forks .22 may -be constructed separately and attached to the tubularmembers I3 -in any convenient or 'suitable manner. .The shifter -forks22 engage .movable members in the transmission .mechanism whereby tomove said members in -either .direction to .effect a change -ingearratidallasis .wellknownin the art.

vEach .of the aligned guide .rods .1 is Vfurther `provided .withastopcollar .-.23 between the ends of the tubular shifter member and thehousing member I.

The-cover plateisprovided with a suitable vent or breather. cap 5.24.whereby the interior'ofV the shifter .mechanism .and .transmissionhousing is in .communication with the .outer atmosphere. Such a vent isprovided to equalize the pressure within the .housing .and .the .outer.atmosphere so that in .the .event .the shifter mechanism .should leakand .allow .iuid under pressure .toenter the transmission. casing,.suchpressure will be dissipated through the vent-.24 to. guard againstits .forcing .lubricating oil from the working parts of the transmissionmechanism.

Each of .thettings .l2 is connected,.through a suitahie control valvemechanism `(not shown) -to a Asnurceof "uid..pressure whereby .fluidunder pressure may ,be selectively admitted to theshifter-mechanism.through any one o1 thettingsIZ.

4 Each of the aligned guide rods 1 is provided with an enlarged bore 31adjacent its free end, said bore beingv of sulicient diameter toaccommodate the stop nut 33, as clearly shown in the drawings. The lineA in Figures 3, 4 and 5 represents the mid position of the mechanism andwhen the mid point of the tubular members I3 lies on line A thecontrolled gear mechanisms are ln neutral.

by the stop collar 23, thus moving its shifter fork 22 and theassociated gear'mechanism to eiect engagement of the selected gears. Thestop co1- lar 23 thus absorbs any continued thrust due to the fluidpressure in the chamber 20 andprevents such thrust from beingtransmitted to the rotat- -i ing parts of the gear mechanism, throughthe fork 22,Y thus preventing undue wear of said parts. Upon release ofthe pressure from the chamber 2Q thespring 2| in theleft-hand chamberwill expand to return the shifter member I3, fork 22 and the gearmechanism to neutral position, that is, the position shown in Figure 2.In the embodiment just described it is necessary that the springs 2| Vbeof equal strength since the neutral position of the shifter member I3 isthat position at which the forces of the opposed springs just balanceeach other. The springs must be so balancedthat the gear mechanismvcontrolled thereby is heldV normally in its neutral or disengagedposition. Y i

As shown in Figure 1, adjacent ends of the two tubularshi-fter membersI3 are provided with opposedconical recesses 25 and 26. Said recessesare opposite each other when the tubular members I3 are in their mid orneutral position as shown. A portion of the housing I is provided witharbore 21 in which a pin 28 is slidably mounted. The `pin 28 is providedwith conical ends V29 and 30 and is of such length that when one end isreceived in one ofthe recesses 25 or 26, its opposite end just clearsthe side of the other tubular member I3. Y Thus, if the tubular memberI3 shown at the top of Figure 1 were shifted either to the right orleft, the conical sides of the recess 26 would force the lpin 2Bdownwardly and into the recess.25 thuslocking the lower tubular memberI3 in its neutral position until such time y described. This embodimentdiffers from that in l Figures 1 and 2in that means are provided forpositivelydetermining the neutral or mid position ofctheqtubular shiftermembers I3 irrespec- ,tive of `therelative Vstrength ofthe springsemployed.

In 4each of the expansible pressure chambers I9 3 Vand 2B 'a plug member30 ispositioned adjacent the partition wall I8. Each of the plug membersl 3ll has rigidly attached thereto a guide member l3|fon which a slide32 is mounted for sliding u s movement into engagementrwith a stop nut33 threaded on the free end of each of the guides 3|.

The nuts-33 vare preferably castellated nuts and .are locked in adjustedposition by means of cotter pins. Vlil'ach of the slide members 32consists of a cylindrical portion 34 and a flanged portion 35 and acompression spring 36 is located between 3 and reacts against the ilange35 and the plug 30.

As shown in Figure 3, the tubular member I3 is in such neutral `positionand it is to be noted that the ange members 35 are in abutment with thestop nuts 33 and also engage the ends of the aligned guide rods 1, thusit will be seen that the tubular member I3 is positioned and maintainedin such neutral position irrespective of the relative strength of thesprings 36 since any excessive force exerted by the stronger of the twosprings is absorbed by the stop nut 33 and does not react against theend of the guide rod 1 to move the tubular shifter member I3 from itsneutral position.

If iiuid under pressure is admitted to one of the expansible chambers,for instance, the left hand chamber I 9, that chamber will be expandedand the tubular shifter member I3 will be moved to the right and theparts will assume the position shown in Figure 4. It will be noted fromFigure 4 that when pressure is admitted to the leftr hand chamber I9 thespring in the right hand chamber will be compressed until the end 38 ofthe cylindrical portion 34 engages the plug 30 and since the ange 35 isin engagement with the end of the right`hand guide rod 1, the shiftermechanism cannot move any lfurther toward the right. Thus, a positivestop is provided to limit the movement of the fork 22 and its controlledgearV mechanism. The parts are so proportioned that the controlled gearmember will be moved a suilicient amount to properly engage with itsassociated transmission element but will not be urged beyond that point.During movement of the parts toward the right as shown in Figure 4, thespring and stop mechanism located in the left-hand cham-ber I9 will vbeineffective and merely move with the shifter member I3 to the right awayfrom the adjacent end of the lefthand guide rod 1. *Y l Upon release ofthe uid vpressure from the chamber I97 the lcompressed spring 36 in thechamber 2i) will move the tubular shifter member I3, its fork 22, andthe controlled gear part to the left. The plug member 3|), guide 3|, andstop nut 33 (in chamber 20) will yalso move to the left with the memberI3, leaving the ange 35 in yabutment with the end of the guide rod 1.Such movement to the left will continue until the stop nut 33 engagesthe outer face of the ange 35 and renders the spring 36 ineffective tomove the parts farther. 'At the same time, the flange 35 in theleft-hand chamber I9 will just reach the end of the left-hand guide rod1 and the shifter mechanism will be in its mid or neutral position.

When the fluid under pressure is admitted to the right-hand chamber 2D,the parts will as,- sume the position shown in Figure 5 with the springand stop elements in the left-hand chamber functioning exactly as didthose in the righthand chamber when the uid under pressure was admittedto the chamber I9.

Although the embodiments of Figures 1 and 3 each show an integralpartition wall in the tubular member I3 as dividing the two expansiblepressure chambers, it is. to lbe understood that any other suitablemeanscould be provided with equal facility. For instance, the partition wallcould be a separate element inserted after the member i3 has been bored.Furthermore, in the embodiment of Figures 3 to 5 the partition wall I8could be eliminated and the plug members 30 engaging a suitable stopcould provide the necessary pressure seal between the chambers. Likewisethe parts 34 and 35 of the slides 32 need not be integral, they could bemade as separate elements or the part 34 could be integral with the plug39.

Although the preferred actuating uid for the gear shifting mechanism ofthis invention is com pressed air, clearly any other suitable pressuretransmitting iiuid could be employed with equal facility and it is notintended that this invention be limited to the use of compressed air.

While two specic embodiments of the invention have been described, theyare intended to be merely illustrative and not to limit the scope of theinvention. It is contemplated that all embodiments falling within thescope of the appended claims be considered as included in the presentinvention.

We claim:

1. A gear shifting mechanism comprising: a support; a pair of axiallyaligned rods carried by said support and having their adjacent endsaxially spaced; a tubular shifter member telescopically slidable overthe adjacent ends of said rods; means in said tubular member, betweenthe ends of said rods, providing a fluid pressure seal therein wherebyto divide the space between said rod ends into a pair of expansiblepressure chambers; a longitudinally slidable member in each of saidchambers, stop means to limit the range of sliding movement of each ofsaid slidable members; a compression spring between each slidable memberand said sealing means; and means for selectively introducing uid underpressure to either of said chambers.

2. A gear shifting mechanism comprising: a support; a pair of axiallyaligned rods carried by said support and having their adjacent endsaxially spaced; a tubular shifter member telescopically slidable overthe adjacent ends of said rods; a, partition wall in said tubular memberbetween the ends of said rods and forming, with said rod ends andtubular member, a pair of expansible chambers; a plug in each of saidchambers adjacent said partition wall, each said plug supporting anaxially extending guide having stop means at its end opposite said plug;a slide on said guide having a portion providing an annular shoulderfacing said plug and a portion extending toward said plug to limit theminimum spacing between said plug and said shoulder; a compressionspring reacting against said plug and said shoulder and urging saidslide into engagement with said stop means and the end of the adjacentrod, the said parts being so proportioned that the distance between theouter ends of said slides, when in engagement with said stops issubstantially equal to the distance between the ends of said rods; andmeans for selectively admitting fluid under pressure to either oi saidchambers.

3. A gear shifting mechanism comprising: a support; a pair of -axiallyaligned rods carried by said support vand having their adjacent endsaxially spaced; a tubular shifter member telescopically slidable overthe adjacent ends of said rods; a partition wall in said tubular memberbetween the ends of said rods and forming, with said rod ends andtubular member, a pair of expansible chambers; a, plug in each of saidchambers adjacent said partition wall, each said plug supporting anaxially extending guide having stop means at its end opposite said plug;a slide on said guide having a portion providing an annular shoulderfacing said plug and a portion extending toward said plug to limit theminimum spacing between said plug and said shoulder; a compressionspring reacting against said plug and said shoulder and urging saidslide into engagement with said stop means and the end of the adjacentrod, the said parts being so proportioned that the distance between theouter ends of said slides, when in engagement with said stops, issubstantially equal to the distance between the ends of said rods; arecess in the end of each of said rods to accommodate said stop meanswhen said slides are in engagement with said rod ends; and axial boresin said rods, communicating with said recesses and a source of uidpressure whereby iiuid under pressure may be selectively admitted toeither of said chambers to effect sliding movement of said tubularshifter member in one direction.

4. A gear shifting mechanism comprising: a support; two pairs of axiallyaligned rods carried by said support and having their adjacent endsaxially spaced; a tubular shifter member telescopically slidable overthe adjacent ends of each pair of rods; fluid pressure means actingwithin said tubular members to selectively slide either tubular memberin either direction from a mid position; stop means for limiting themovement of each tubular member in each direction; expansible springmeans normally urging said tubular members toward said mid position,adjustable stop means to limit the range of action of said spring meansand thereby vary said mid position; a conical recess in the externalsurface of each tubular member, said recesses facing each other whensaid tubular members are in their mid position; a locking member carriedby said support and movable into either recess at the mid position ofsaid tubular members, and means for moving said locking member into therecess in one tubular member when the other tubular member is moved fromits mid position whereby to lock said lone tubular member in its midposition until said other tubular member returns to its mid position.

HARLAND W. CARDWELL. JAMES W. HAUPT.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNT..| ED STATES PATENTS Number Name Date 68,994 King Sept. 17, 1867859,737 Brown July 9, 1907 1,010,054 Irish Nov. 28, 1911 1,141,589Taylor June 1, 1915 2,110,994 Linsley Mar. 15, 1938 2,242,542 PetersonMay 20, 1941 2,403,328 Banning July 2, 194B FOREIGN PATENTS NumberCountry Date 1,193 Great Britain 1868 800,878 France July 21, 1936

